An ADAR that edits transcripts encoding ion channel subunits functions as a dimer

Angela Gallo, Liam P. Keegan, Gillian M. Ring, Mary A. O'Connell

Research output: Contribution to journalArticlepeer-review


In this report, we establish that Drosophila ADAR (adenosine deaminase acting on RNA) forms a dimer on double-stranded (ds) RNA, a process essential for editing activity. The minimum region required for dimerization is the N-terminus and dsRNA-binding domain I (dsRBD1). Single point mutations within dsRBD1 abolish RNA-binding activity and dimer formation. These mutations and glycerol gradient analysis indicate that binding to dsRNA is important for dimerization. However, dimerization can be uncoupled from dsRNA-binding activity, as a deletion of the N-terminus (amino acids 1-46) yields a monomeric ADAR that retains the ability to bind dsRNA but is inactive in an editing assay, demonstrating that ADAR is only active as a dimer. Different isoforms of ADAR with different editing activities can form heterodimers and this can have a significant effect on editing in vitro as well as in vivo. We propose a model for ADAR dimerization whereby ADAR monomers first contact dsRNA; however, it is only when the second monomer binds and a dimer is formed that deamination occurs.

Original languageEnglish
Pages (from-to)3421-3430
Number of pages10
JournalEMBO Journal
Issue number13
Publication statusPublished - Jul 1 2003


  • ADAR
  • Dimer
  • Drosophila
  • Ion channels
  • RNA editing

ASJC Scopus subject areas

  • Genetics
  • Cell Biology


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